res_pjsip_outbound_publishing: After unloading the library won't load again

The same thing was happening in res_pjsip_publish_asterisk. When the library
was unloaded it did not unregister the object type from sorcery. Subsequent
loads resulted in a failed load due to the sorcery type already existing.

Change-Id: Ifdc25e94e4cd40bc5a19eb4d0a00b86c2e9fedc9

res/res_pjsip_outbound_publish.c

@@ -1162,6 +1162,7 @@ static int load_module(void)
 
 	if (ast_sorcery_object_register(ast_sip_get_sorcery(), "outbound-publish", sip_outbound_publish_alloc, NULL,
 		sip_outbound_publish_apply)) {
+		ast_log(LOG_ERROR, "Unable to register 'outbound-publish' type with sorcery\n");
 		return AST_MODULE_LOAD_DECLINE;
 	}
 
@@ -1234,6 +1235,7 @@ static int unload_module(void)
 			"in the allowed time\n", unloading.count);
 	} else {
 		ast_verb(5, "All items successfully unpublished\n");
+		ast_sorcery_object_unregister(ast_sip_get_sorcery(), "outbound-publish");
 	}
 
 	return res;

res/res_pjsip_publish_asterisk.c

@@ -862,6 +862,7 @@ static int load_module(void)
 	ast_sorcery_apply_default(ast_sip_get_sorcery(), "asterisk-publication", "config", "pjsip.conf,criteria=type=asterisk-publication");
 
 	if (ast_sorcery_object_register(ast_sip_get_sorcery(), "asterisk-publication", asterisk_publication_config_alloc, NULL, NULL)) {
+		ast_log(LOG_ERROR, "Unable to register 'asterisk-publication' type with sorcery\n");
 		return AST_MODULE_LOAD_DECLINE;
 	}
 
@@ -919,6 +920,7 @@ static int unload_module(void)
 	ast_sip_unregister_publish_handler(&asterisk_mwi_publication_handler);
 	ast_sip_unregister_event_publisher_handler(&asterisk_devicestate_publisher_handler);
 	ast_sip_unregister_event_publisher_handler(&asterisk_mwi_publisher_handler);
+	ast_sorcery_object_unregister(ast_sip_get_sorcery(), "asterisk-publication");
 	return 0;
 }